This invention relates to an improved container for the chemical sterilizing or disinfecting of soft contact lenses and, more particularly, to a device for the venting from contact lens holding appliances of gases liberated by contact lens solutions.
Hydrophilic contact lenses are commonly cleaned or sterilized in a bactericide solution, such as a 3% solution of hydrogen peroxide along with a hydrogen peroxide decomposition catalyst, for several hours. By means of the catalyst, the hydrogen peroxide is rapidly decomposed into water and oxygen. If the container holding the solution is completely sealed, the liberated gas may create undue pressure causing the container or case to fracture, thereby destroying its integrity. Therefore, it is necessary to vent the liberated oxygen from whatever appliance contains the solution and lenses.
A prior art venting method was simply to allow the oxygen to escape through an opening in the top of the case, but the liquid could also spill out if the case was tilted or turned over. Such loss of solution would likely cause the lens to dehydrate. Also, any solution which passed through the opening could damage the clothing of the user.
U.S. Pat. No. 4,396,583 to LaBoeuf and U.S. Pat. No. 4,637,919 to Ryder et al. disclose vented lens disinfecting appliances which employ a hydrophobic membrane filter disposed across the vent that is impermeable to the solution but is permeable to the liberated oxygen gas. The disadvantages of that filter include the clogging of the membrane pores during repeated uses of the appliance due to dehydrate solution ingredients and various materials released into solution from the lens surfaces. Over time, the gases liberated from the disinfecting solution cannot be satisfactorily vented, possibly fracturing the case.